An IQ modulator shapes and samples an input signal to generate a series of discrete sampled values. Each sampled value includes an in-phase (I) component and a quadrature (Q) component, collectively referred to as a sampled IQ value. An IQ trajectory is a path derived from discrete sampled IQ values sampled from the input signal. The sampled IQ values are plotted on an IQ graph, with the origin (0,0) defined as the zero value for both the in-phase (I) component and the quadrature (Q) component. The sampling rate determines the number of discrete sampled IQ values. The higher the sampling rate, the more points that define the IQ trajectory. The IQ trajectory is ideally a smooth curve representing an infinite number of discrete sampled IQ values. In practice, there is always some finite number of sampled values, as defined by the sampling rate.
By hardware limitations, an IQ trajectory through the origin generates distortion in a corresponding output signal. Corrective processing of the sampled IQ values at the origin can improve the performance of the signal processing circuit. When IQ values at the origin are processed through a filter and over-sampled many transients occur as consecutive IQ values at the origin are traversing about, around and through the origin. Processing of the IQ values is desirable to remove these transients.